1. Field of Invention
The present invention relates to a flat lamp and cathode plate thereof. More particularly, the present invention relates to a field emission flat lamp and cathode plate thereof.
2. Description of Related Art
The luminescence principle of the field emission display is to absorb electrons in the top end of materials by utilizing the electric field in a vacuum environment, and the field emission electrons from the cathode plate accelerate to be absorbed and bombard to the fluorescent powder of the anode due to the positive voltage over the anode, thus the luminescence occurs. The cathode plate is used as the field electron emission source, and the anode plate is used as the light-emitting source. The luminescence occurs with the electrons emitted from the cathode plate bombarding to the fluorescent layer of the anode plate. When the field emission display is used as the backlight source of other elements, it is a flat luminous element with a more preferred light uniformity compared with the cold cathode fluorescent lamp (CCFL) or the light emitting diode (LED).
FIG. 1 is a top view of a cathode plate of a well-known field emission flat lamp. Please refer to FIG. 1, on the well-known cathode plate 100 of the field emission flat lamp (not shown), gate structures 110 and cathode structures 120 are arranged interlacedly in parallel. The emission layer 130 is mixed to starchiness first, and disposed in strip-form on the cathode structures 120 by screen printing. However, bubbles may reside inside the starched emission layer 130, i.e. there are tiny bubbles in the emission layer 130. Furthermore, because the emission layers 130 are arranged in strip-form on the cathode structures 120, the accumulation of the large amount of the emission layers 130 makes removing the bubbles even more difficult. If the bubbles can not be removed, the field-emission electric field distribution will be un-uniform during the luminescence of the field emission flat lamp, such that the light uniformity of the field emission flat lamp is poor. Similarly, the gate structures 110 and cathode structures 120 are also made of starched form before screen printing, which leads to the problem of bubble occurrence and removal difficulty.
Since the light source uniformity required by the current displays is of an extremely high standard, if the conventional field emission flat lamp is to be used as a light source for displays, a diffusion film is required to improve the light uniformity, which will increase the assembling complexity of displays and further increase the cost of raw materials and the assembling process. Thus, the conventional field emission flat lamp is not suitable for being widely applied in the market.